@InProceedings{MortariniDAOBGSTAMC:2021:InAtSt,
               author = "Mortarini, Luca and Dias J{\'u}nior, Cl{\'e}o Quaresma and 
                         Acevedo, Otavio and Oliveira, Pablo and Brondani, Daiane and 
                         Giostra, Umberto and S{\"o}rgel, Matthias and Tsokankunku, 
                         Anywhere and Ara{\'u}jo, Alessandro and Machado, Luiz Augusto 
                         Toledo and Cava, Daniela",
          affiliation = "{Institute of Atmospheric Sciences and Climate} and {Instituto 
                         Nacional de Pesquisas da Amaz{\^o}nia (INPA)} and {Universidade 
                         Federal de Santa Maria (UFSM)} and {Universidade Federal do Rio 
                         Grande do Norte (UFRN)} and {Instituto Nacional de Pesquisas da 
                         Amaz{\^o}nia (INPA)} and {Universita\̀ degli Studi di 
                         Urbino “Carlo Bo”} and {Max Planck Institute for Chemistry} and 
                         {Max Planck Institute for Chemistry} and {Empresa Brasileira de 
                         Pesquisa Agropecu{\'a}ria (EMBRAPA)} and {Instituto Nacional de 
                         Pesquisas Espaciais (INPE)} and {Institute of Atmospheric Sciences 
                         and Climate}",
                title = "Influence of Atmospheric Stability on the flow dynamics within and 
                         above a dense Amazonian forest",
                 year = "2021",
         organization = "EGU General Assembly",
            publisher = "EGU",
             abstract = "This study provides a detailed analysis of the influence of 
                         atmospheric stratification on the flow dynamics above and within a 
                         dense forest for a 19-days campaign at the Amazon Tall Tower 
                         Observatory (ATTO) site. Observations taken at seven levels within 
                         and above the forest along an 81-meter and a 325-meter towers 
                         allow a unique investigation of the vertical evolution of the 
                         turbulent field in the roughness sublayer and in the surface layer 
                         above it. Five different stability classes were defined on the 
                         basis of the behavior of turbulent heat, momentum and CO2 fluxes 
                         and variance ratio as a function of h/L stability parameter (where 
                         h is the canopy height and L is the Obukhov length). The novelty 
                         is the identification of a super-stable (SS) regime (h/L>3) 
                         characterized by extremely low wind speeds, the almost completely 
                         suppression of turbulence and a clear dominance of submeso motions 
                         both above and within the forest. The obtained data classification 
                         was used to study the influence of atmospheric stratification on 
                         the vertical profiles of turbulent statistics. The spectral 
                         characteristics of coherent structures and of submeso motions 
                         (that may influence the energy and mass exchange above the Amazon 
                         forest) have been analyzed by wavelet analyses. The role of the 
                         main structures in momentum, heat and CO2 transport at the 
                         different levels inside and above the forest and in different 
                         diabatic conditions was thoroughly investigated through 
                         multiresolution and quadrant analyses. In unstable and neutral 
                         stability, the flow above the canopy appears modulated by 
                         ejections, whereas downward and intermittent sweeps dominate the 
                         transport inside the canopy. In the roughness sublayer (z £ 2h) 
                         the coherent structures dominating the transport within and above 
                         the canopy have a characteristic temporal scale of about 100 sec, 
                         whereas above this layer the transport is mainly driven by larger 
                         scale convection (temporal scale of about 15 min). In stable 
                         conditions the height of roughness sublayer progressively 
                         decreases with increasing stability reaching the minimum value 
                         (z<1.35h) in the SS regime. Above the canopy the flow is clearly 
                         dominated by ejections but characterized by a higher intermittency 
                         mainly in SS conditions. On the other hand, the rapid shear stress 
                         absorption in the highest part of the vegetation produces a less 
                         clear dominance of sweeps and a less defined role of odd and even 
                         quadrants inside the canopy in the transport of momentum, heat and 
                         CO2. In the weakly stable regime (0.15<h/L<1) transport is 
                         dominated in the roughness sublayer by canopy coherent structures 
                         with a characteristic temporal scale of about 60 sec. As stability 
                         increases the influence of low-frequency (submeso) processes, with 
                         a temporal scale of 20-30 min, on flow dynamics progressively 
                         increases and becomes dominant in the SS regime where the buoyancy 
                         strongly dampens or completely inhibits turbulent structures 
                         whereas the large-scale oscillations propagate in the interior of 
                         the canopy modulating the heat and CO2 transport.",
  conference-location = "Online",
      conference-year = "19-30 apr.",
                  doi = "10.5194/egusphere-egu21-12971",
                  url = "http://dx.doi.org/10.5194/egusphere-egu21-12971",
             language = "en",
           targetfile = "EGU21-12971-print.pdf",
        urlaccessdate = "06 maio 2024"
}